Tube bender having a support sleeve with a circular aperture merging into an oval aperture



Ap'z'fi 21, 1959 A. HUET 2,882,953 TUBE BENDER HAVING A SUPPORT SLEEVEWITH A CIRC APERTURE MERGING INTQ AN OVAL APERTURE Filed Oct. 6. 1954ULAR fl/VDRE #067 INVENTOR.

United States Patent TUBE BENDER HAVING A SUPPORT SLEEVE WITH A CIRCULARAPERTURE MERGING INTO AN OVAL APERTURE Andre Huet, Paris, France,assi'gnor to Combustion Engineering, Inc., New York, N.Y., a corporationof Delaware The present invention relates to tube bending andparticularly to an improved apparatus for making return bends inmetallic tubes.

In bending a straight tube it is conventional to draw the tube on arotating bending wheel, in the groove of which the tube is received. Inthe apparatus of this type, the tube is applied against the bendingwheel and held in position by two retainer wheels.

In his earlier patent, No. 2,689,596, applicant proposed in order tofacilitate the bending of tubes, especially over a narrow radius ofbending, to heat the tube before bending, especially in the portionwhich will become the crotch portion of the bend.

In the case of thin wall tubes (i. e. tubes whose wall thickness is lessthan of the diameter of the tube) and more especially in the case whereit is necessary to heat the tube, it can happen that the retainerwheels, crushing the low-resistance metal, will cause a buckling, i.e. aflattening of the tube cross-section and wrinkles which spoil theattainment of a perfect bend.

To remedy this inconvenience, the applicant has devised a tube-supportapparatus, consisting of a sleeve, preferably in two parts each havingtwo complementary pieces, completely surrounding the tube in advance ofits insertion on the bending wheel, and guiding it almost up to thepoint at which the tube begins to assume its curvature on the bendingwheel. This support sleeve is fixed to the bench carrying the bendingwheel and its presence, in addition to assuring delivery of the tubewithout flattening or wrinkling, to the bending wheel, permitselimination of one of the retainer wheels.

Moreover, in the case of dealing with tubes where, for a certain length,the cross section is previously ovalized to facilitate bending, thesupport sleeve must have an oval cross section groove corresponding tothat of the tube, but it is provided that there be at the entrance ofthe support sleeve and over a certain length, a groove of a crosssection such that it can serve as well for passage of the ovalized tubeas for the same tube still having its cylindrical cross section. In thisway the part of the tube that remains cylindrical can enter the sup portsleeve during the end of the bending operation, and it is only necessaryto ovalize the length of straight tube which has to be bent.

The support sleeve can even be such that it will produce ovalization ofa tube as the latter passes through it under the efiect of tractionexerted by the bending wheel.

In the drawings:

Figure 1 is a plan view of the tube matrix or support placed on thebending apparatus ahead of the bending in accordance with the invention;

Figure 2 is a larger scale section on the line 2-2 of Fig. 1.

Figure 3 is a larger scale section on the line 3-3 of Fig. 1.

As can be seen in Figure 1, a tube a that is to be bent is engaged by arotating bending wheel 10 having a groove of usual shape, in which thetube is held by a single retention wheel 12. A device for gripping atube in accordance with the invention is shown in Figure 1. It comprisesa drawing unit which can be composed of finger 14 mounted on the bendingor shaping wheel 10. The finger 14 is formed with an aperture thatreceives and surrounds the tube. The part of finger 14 at the base ofthis aperture which bears on the outside of tube a may have teeth whichbite on this part of the tube. A bracket 16 fixed to the finger 14supports a jaw 18 pivoting on bracket 16 whose end penetrates to theinterior of tube a to apply itself on the inner wall of the tube. Theend of jaw 18 may also have indentations or teeth which bear against andgrip on the internal wall of tube a.

Gripping of the tube a between fingers 14 and jaw 18 is accomplishedunder the efiect of the push exerted by a jack 20 mouted on the bracket16. The jack acts via links on the end of pivoted jaw 18 on the one handand on a fixed point on bracket 16 on the other hand. This grippingmeans is more fully described in my co-pending application, Serial No.460,590 filed October 6, 1954.

According to the invention, before engaging the bending wheel, tube a issupported by a guide, preferably in two complementary pieces 22, 24(Figs. 1 and 2), between which there is a groove whose cross sectioncorresponds to that of the tube to be treated; part of the tube a can beovalized beforehand as shown in Figs. 1 and 2. Piece 22 is fastened tothe bench on which the Wheel 10 turns, and the second part 24 of thematrix engages in part 22 as shown in Fig. 2. It also can be fastened tothe bench.

A heating device 26 is located between the groove of the rotatingbending wheel 10 and the adjacent end of the support matrix 22, 24 asseen in Fig. l, in such a way as to assure during the bending thecontinuous heating of the part of the tube which will form the crotch ofthe bend, this occurring immediately before thee tube takes its curve onthe bending wheel 10. After this the tube is cooled again, for exampleby contact with the grooves of the wheels 10, 12 which can have aninterior cooling circulation of a sort that the tube, once it hasassumed its curve, will regain its rigidity when cold.

-In the case of a thin walled tube, the cylindrical cross section tubemay previously to bending be ovalized over a length (AB) correspondingto the length of the bend to be formed (as seen in Figs. 1 and 2). Thelong axis (EF) of the oval is in the plane of symmetry perpendicular tothe axis (X) of the bending wheel.

As it is preferable only to ovalize beforehand the length (AB) of tube acorresponding in general to the length of the tube to be bent, it isnecessary to arrange, at the end of the bending movement, that a certainportion of the tube a that has remained cylindrical, can penetrate intothe support matrix 22, 24 without passing over the bending wheel. Thisis why, according to the invention, the support matrix is in two parts.The part of the matrix 22, 24 located closest to the wheel 10 has anaperture of oval section and the outer part 32, 34 of the said matrixaperture has a section such that (as seen in Fig. 3) it may serve at thesame time for the passage of the oval section of the tube (indicated inoutline by dot-dashes G) and the part of the tube that is stillcylindrical (shown in dotted outline H).

The aperture inside the support sleeve 22, 24 can moreover be such thatit changes gradually from a cylindrical to an oval shape, in such a waythat the actual ovalization of part of the tube takes place in the saidsupporting matrix 22, 24 under the force of traction exerted on the tubeby the wheel 10.

It goes without saying that modifications in details of construction inthe invention may be made without thus deviating from its scope.

- WltaLI claim is:

In apparatus for bending a cylindrical tube having a,

portion of ovalized section followed by a portion of normal circularsection of a zdiameter slightly greater than that- .of the short axis ofthe ovalized section, which apparatus has .aibending wheel provided witha, groove for receiving the ovalized section of the tube, the improvement comprising; a tube support and guide sleeve positioned immediatelyforward of thelocation in which the tube first assumes curvature on thebending wheel and formed with an aperture of ovalized section,corresponding to that of the tube, in a location adjacent the bendingwheel and merging into an aperture, more remotely located from thebending wheel, which has a cross-section corresponding on one axis tothe major axis of the ovalized section of the tube and on an axis normalthereto corresponding to the said circular sectionof the tube.

References Cited inithe file of this patent UNITED STATES PATENTS434,804 Quiggin Aug. 19, 1890 1,135,875 Brinkman Apr. 13, 1915 1,924,734Brown Aug. 29, 1933 1,967,487 Waisner July 24, 1934 2,229,462 Kurtz Jan.21, 1941 2,267,774 Wall -Dec. 30, 1941 FOREIGN PATENTS 494,207 CanadaJuly 7, 1953

